Magnetic Gearbox

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Enhancing Power Generation

The conversion of mechanical energy to electrical energy – or vice versa – is achieved with large electromechanical volumes at low rotation speeds. Gears are a convenient way to convert the slow speed, high torque wind energy but are the highest cost and most failure-prone component within the drive system.

Conventional mechanical gearboxes are beset by compromised life and ongoing maintenance issues. If direct drive conversion is employed, the equipment is huge in both physical size and cost, due to the properties indigenous to materials available and practical today. Mechanical gears with large ratios are anything but small, and the difficulty has much to do with the number of teeth that can be engaged at one time. Sharing teeth increases costs considerably due to mechanical machining requirements of multiple stages and parallel linkages. The very nature of intermittent wind can cause unpredicted non-linear loads or overload causing tooth and bearing failures that are also costly and cause energy production losses.

We propose an alternative to mechanical gearboxes using magnetic fields. Calculations suggest that a magnetic gear with a 1/50th sized conventional generator could replace an electromechanical system 8 times larger. When a magnetic field simulation proved this 8:1 advantage over a superconducting direct drive alternative, our team became convinced that this technology could make significant inroads in the evolution of advanced wind power generation. This magnetic gear scaled to a 100:1 ratio will be even more efficient and cost effective at lower volumes, and is able to be entirely engaged at once.

Through guided research programs by the US Department of Energy and the US Office of Naval Research, we have developed and tested a prototype magnetic cycloid gearbox that has shown significant advantages over the most advanced mechanical gears on the market as well as other magnetic concepts and prototypes. Both the rotor and the stator have been intricately designed to include magnetic arrays that maximize lock-in force. The arrays span the full perimeter of the gear while maintaining a precise air gap for optimized efficiency even if scaled to 100:1 gear ratio. The magnetic cycloid gear has been developed in a wide array of applications including slow head hydro and wind power generation. The cycloid gear has many advantages over conventional and even magnetic gear concepts and prototypes, and AMT has produced a 10 kilowatt-hour prototype that has undergone testing and proven over 96% efficient. It is now ready for commercialization.

The magnetic gearbox opens the possibility of a device with an expected 30 year life cycle and minimizes the footprint of the generator required for the electrical conversion. It is failsafe and maintenance free, two characteristics never before applied to gearboxes. The magnetic gear bypasses the long lead times for mechanical gears and shortens the time to deployment. This technology creates a cost effective way to tap into the renewable kinetic energies up to at exceedingly high gear ratios.

As renewable energy generation becomes standard, providers must focus on high efficiencies to adequately serve the market as well as long life cycles to protect the bottom line. We are seeking a strategic partnership to collaborate in scaling its prototype gear for wind applications and engaging in marketing and sales activities.